This method works for cod fish but I suspect it will work for other bullet shaped fish.
Tools required - A sharp knife, preferably a fish knife but a Swiss Army Knife will also do.
Pierce the skin from anus to gills and gut the fish. Discard or retain the entrails depending on whether you have some arcana or composting to perform.
Remove the tail just where the flesh ends.
Remove the dorsal fin structure by cutting a few millimeters below it.
Place the fish top side up on the cutting board. Break the back bone by inserting your knife just behind the head where the body cavity is largest.
The next move requires a small amount of forcefulness.
After breaking the backbone the head should hinge quite well. Holding the fish round its fleshy middle onto the cutting board , grab the head with your other hand, bend it completely backward and pull strongly towards the tail of the fish . As long as you dont twist the fish then the skin should start to peel away from the flesh. Dont panic the ripping sound is normal.
Keep peeling backwards until the skin is completely removed. You should now have a skinless but not boneless chunk of fish.
Carry on preparation until you feel you have an edible fish.